docs: add examples for tcp elements, also use correct section name. Fixes #564139

Updated the examples in the README to actually work. Add them to api docs. Tests
the api-docs and fix the section names to make the docs actualy show up.
The example for "tcpserversrc" needs review (might be an element bug).

gst/tcp/README

@@ -8,22 +8,25 @@ TESTS
 -----
 Use these tests to test functionality of the various tcp plugins
 
-* server: nc -l 3000
+* server: nc -l -p 3000
   client: nc localhost 3000
   everything you type in the server is shown on the client
   everything you type in the client is shown on the server
 
-* server: nc -l 3000
+* server: nc -l -p 3000
   client: gst-launch tcpclientsrc protocol=none port=3000 ! fdsink fd=2
   everything you type in the server is shown on the client
 
-* server: nc -l 3000
+* server: nc -l -p 3000
   client: gst-launch fdsrc fd=1 ! tcpclientsink protocol=none port=3000
   everything you type in the client is shown on the server
 
 * server: gst-launch tcpserversrc protocol=none port=3000 ! fdsink fd=2
   client: gst-launch fdsrc fd=1 ! tcpclientsink protocol=none port=3000
 
+* server: gst-launch fdsrc fd=1 ! tcpserversink protocol=none port=3000
+  client: gst-launch tcpclientsrc protocol=none port=3000 ! fdsink fd=2
+  -> Received first buffer without caps set
 
 TODO
 ----

gst/tcp/gsttcpclientsink.c

@@ -19,9 +19,18 @@
  */
 
 /**
- * SECTION:tcpclientsink
+ * SECTION:element-tcpclientsink
  * @see_also: #tcpclientsrc
  *
+ * <refsect2>
+ * <title>Example launch line</title>
+ * |[
+ * # server:
+ * nc -l -p 3000
+ * # client:
+ * gst-launch fdsrc fd=1 ! tcpclientsink protocol=none port=3000
+ * ]| everything you type in the client is shown on the server
+ * </refsect2>
  */
 
 #ifdef HAVE_CONFIG_H

gst/tcp/gsttcpclientsrc.c

@@ -19,9 +19,18 @@
  */
 
 /**
- * SECTION:tcpclientsrc
+ * SECTION:element-tcpclientsrc
  * @see_also: #tcpclientsink
  *
+ * <refsect2>
+ * <title>Example launch line</title>
+ * |[
+ * # server:
+ * nc -l -p 3000
+ * # client:
+ * gst-launch tcpclientsrc protocol=none port=3000 ! fdsink fd=2
+ * ]| everything you type in the server is shown on the client
+ * </refsect2>
  */
 
 #ifdef HAVE_CONFIG_H

gst/tcp/gsttcpserversink.c

@@ -19,9 +19,18 @@
  */
 
 /**
- * SECTION:tcpserversink
+ * SECTION:element-tcpserversink
  * @see_also: #multifdsink
  *
+ * <refsect2>
+ * <title>Example launch line</title>
+ * |[
+ * # server:
+ * gst-launch fdsrc fd=1 ! tcpserversink protocol=none port=3000
+ * # client:
+ * gst-launch tcpclientsrc protocol=none port=3000 ! fdsink fd=2
+ * ]| 
+ * </refsect2>
  */
 
 #ifdef HAVE_CONFIG_H

gst/tcp/gsttcpserversrc.c

@@ -19,9 +19,18 @@
  */
 
 /**
- * SECTION:tcpserversrc
+ * SECTION:element-tcpserversrc
  * @see_also: #tcpserversink
  *
+ * <refsect2>
+ * <title>Example launch line</title>
+ * |[
+ * # server:
+ * gst-launch tcpserversrc protocol=none port=3000 ! fdsink fd=2
+ * # client:
+ * gst-launch fdsrc fd=1 ! tcpclientsink protocol=none port=3000
+ * ]| 
+ * </refsect2>
  */
 
 #ifdef HAVE_CONFIG_H